Last month an unfamiliar expression appeared in the Australia media. A "subprime mortgage crisis" was unfolding in the United States. Homeowners across America were defaulting on loan payments and economists warned of major financial fallout occurring anywhere from Paris to Beijing to Melbourne. But why should a foreclosure in Cleveland affect a hedge fund in Sydney?

As Four Corners reports, Australia, along with the rest of the world, is at risk of a virulent economic virus thanks to financial globalisation where everything is interconnected through a sophisticated form of pass the parcel. And even more alarmingly, no-one knows just how bad it might get.

"A perfect storm."

Reporter Paul Barry explains how the subprime market was created through a unique set of circumstances beginning with the fallout from September 11. The program charts the rise of easy credit to the point where mortgage brokers were running out of customers. Enter the subprime loan, the loan you could get when, as one real estate agent tells Four Corners, the only criterion was to see if the client was breathing.

The program reveals how predatory lenders were unregulated and often unscrupulous, targeting people they knew couldn't pay. The broker would make the loan, take a fat commission, and pass on the responsibility as quickly as possible. One lawyer tells the program: "It's American capitalism at its worst."

"The last one out of Cleveland please turn off the lights."

A 'market correction' is a nice economic expression that goes nowhere near capturing the heartbreaking human cost of this financial disaster. This year and the next more than two million American families will lose their homes. Four Corners visited Cleveland, Ohio, where the streets are lined with empty houses, dead gardens and demolition notices pinned to the front doors. One in 20 homes are now in foreclosure. Paul Barry talks with home owners facing eviction and the lawyers trying to save them.

"The crisis is just beginning."

US economists are warning that the worst may still be to come. They are even talking about the "R" word: recession. And one leading financial expert warns if the US slips into recession: "I don't think anybody anywhere in the world is going to be immune. It's a question of degree rather than whether they're affected."